In U.S. Pat. No. 4,880,551, there are provided synergistic antioxidant compositions containing (a) 1-[di(4-octylphenyl)aminomethyl]tolutriazole and (b) an antioxidant selected from the group consisting of methylenebis(di-n-butyldithiocarbamate), 2,6-di-t-butyl-4-sec-butylphenol, 2,6-di-t-butyl-4-methylphenol and butylated phenol mixture and wherein the ratio of the tolutriazole compound to the antioxidant ranges from about 1:4 to about 4:1.
In U.S. Pat. No. 6,743,759, there are provided improved antioxidant, antiwear/extreme pressure additive compositions containing (a) methylenebis(di-n-butyldithiocarbamate) and (b) a diphenylamine derivative of tolutriazole or benzotriazole wherein the (a):(b) mass percent ratio ranges from above about 4:1 to about 50:1 and lubricating compositions containing the same.
U.S. Applications 20100173808, 20080200357 and 20040038835 and U.S. Pat. Nos. 4,734,209, 5,580,482 and 6,410,490 describe derivatized triazoles, including a C7-C13 aralkyl derivative (equivalent to di-C1-C7 alkylated diphenylamine) but do not specifically reference di-octyldiphenylamine (or higher) derivatives of triazole and do not teach the use of methylenebis(di-n-butyldithiocarbamate). In addition, these references do not show any examples of the preparation or application of diphenylamine derivatives of triazole.
U.S. Patent Application 2016/0068781 describes combinations of alkylated phenyl-alpha-naphthylamine (“APANA”), alkylated diphenylamine derivatives of tolutriazole, and methylenebis(di-n-butyldithiocarbamate). While that reference also suggests alkylated diphenylamine derivatives of triazole, there is no discussion of such compounds having alkyl groups being C8 or higher; and no suggestion that by using such C8 or higher alkylated diphenylamine derivatives of triazole in combination with methylenebis(di-n-butyldithiocarbamate), excellent results can be achieved without the presence of the required APANA). Thus, the present invention covers an additive combination or lubricating composition comprising the additive composition comprising C8 or higher alkylated diphenylamine derivatives of triazole in combination with methylenebis(di-n-butyldithiocarbamate), in which said composition is free or substantially free of APANA.
It has been discovered that methylenebis(di-n-butyldithiocarbamate) when used in conjunction with an alkylated diphenylamine derivative of a 1,2,4-triazole (henceforth “triazole derivative”), at a ratio of above about 1:2 to about 50:1, shows a significant synergistic effect with improved antioxidant performance in lubricants over that which is observed with a diphenylamine derivative of benzotriazole or tolutriazole.